add-tgmb-node

name	add-tgmb-node
description	Add a custom designer-style Texture Graph node to the TextureGraphMaterialBridge Unreal plugin from a natural-language description. Use when Codex is asked to create, scaffold, implement, or wire a new `UTG_Expression_TGMB_*` node, shader-backed Texture Graph expression, procedural/filter/adjustment node, node settings, pins, or shader entry point in this repo.

Add TGMB Node

Workflow

Use this skill inside the unreal-texture-graph-to-shader repository. Start by reading references/project-patterns.md, then inspect the closest existing node before editing.

1. Turn the request into a node spec:

   • Display name, C++ suffix, category, tooltip.
   • Input texture pins, output texture pins, settings, defaults, and UI clamp ranges.
   • Shader behavior, expected fallback behavior for missing inputs, and whether the node is tile-aware.

2. Choose the closest local pattern:

   • Texture filter: source texture plus one output, like Highpass, Bevel, or SlopeBlur.
   • Generator: settings-only output, like Clouds2, Cells1, or TileGenerator.
   • Multi-input blend: several source textures, like NormalCombine or MultiMaterialBlend.
   • Multi-output node: one expression evaluates multiple transform outputs, like FloodFill or CurvatureSmooth.

3. Edit the shared designer-node files unless the user explicitly asks for a new file layout:

   • Source/TextureGraphMaterialBridge/Public/TextureGraphMaterialBridgeDesignerExpressions.h
   • Source/TextureGraphMaterialBridge/Private/TextureGraphMaterialBridgeDesignerExpressions.cpp
   • Source/TextureGraphMaterialBridge/Private/TextureGraphMaterialBridgeDesignerTransforms.h
   • Source/TextureGraphMaterialBridge/Private/TextureGraphMaterialBridgeDesignerTransforms.cpp
   • Shaders/Expressions/TGMB_DesignerNodes.usf
   • Shaders/TGMB_DesignerCommon.ush only for reusable shader helpers.

4. Keep the wiring complete:

   • Add the UTG_Expression_TGMB_* class with TG_DECLARE_EXPRESSION, Evaluate, title, tooltip, FTG_Texture pins, and TG_Setting metadata.
   • Add the Evaluate implementation that calls UE::TextureGraphMaterialBridge::FDesignerTransforms::Create*.
   • Add the FSH_TGMB* shader wrapper class and parameter struct.
   • Add the FDesignerTransforms::Create* declaration and implementation.
   • Add IMPLEMENT_GLOBAL_SHADER.
   • Add the FSH_TGMB* pixel shader function and any needed global parameters.

5. Preserve project conventions:

   • Use MinimalAPI for expression classes.
   • Use FTG_Texture for Texture Graph image pins.
   • Use TextureHelper::GetBlack() for absent color/source data unless a mask/scale/default strength should be white.
   • Use CombineIfNeeded before passing input blobs to shader jobs.
   • Use BuildOutputDesc(DesiredDesc, Reference) for input-sized outputs and BuildOutputDesc(DesiredDesc, nullptr) for generators.
   • Use FTileInfo and TileInfo_fromCurrentTileToLayer(UV) for tile-aware/procedural UVs.
   • Add JobArg_ForceTiling for procedural generators that should evaluate per tile like existing cells/noise nodes.

6. Validate after editing:

   • Run rg -n "NewNodeSuffix|FSH_TGMBNewNode|CreateNewNode" Source Shaders to confirm every wiring point exists.
   • Build with the project script when the Unreal environment is available: powershell -ExecutionPolicy Bypass -File scripts\Build-TextureGraphMaterialBridgeInProject.ps1.
   • If building is unavailable, state that clearly and list the structural checks performed.

Output Style

When finished, summarize the node behavior, files changed, and verification. Mention any assumptions made from an underspecified description.